1. Field of the Invention
The present invention relates to an image projection apparatus for projecting an image recorded in a film sheet such as a microfiche onto a screen, a photosensitive body or the like.
2. Description of the Prior Art
In a conventional apparatus of this type, a carrier consists of a right-and-left moving member and a back-and-forth moving member placed thereon, and movement of the carrier is controlled. A microfiche is set on the carrier and is moved two-dimensionally, and a desired one of the microimages formed in a matrix form on the microfiche is retrieved in response to a predetermined address and is located on an optical path of a projection optical system.
At the time of replacement of one microfiche F with another, when an operator depresses an eject key on a keyboard, the movement control device is actuated to move the carrier to the eject position so as to easily access the microfiche. An upper transparent plate holding the microfiche F is opened by an opening/closing mechanism and is kept in an open position.
In this state, the operator removes the used microfiche and inserts a new one. The operator enters a command at the keyboard to close the transparent plate, so that the control device causes the carrier to return to the base position Thereafter, predetermined address access is performed.
When the operator removes the microfiche at the eject position and does not load a new microfiche there, the operator must enter the command for closing the transparent plate and turn off the power switch.
On the other hand, when the operator loads a new microfiche and continues projection, the operator does not forget entering the command for closing the upper transparent plate since the new microfiche must be clamped between a pair of transparent plates.
However, at the end of operation, the operator often forgets to close the upper transparent plate and simply turns off the power switch. The upper transparent plate is thus kept open. In this state, the operator may erroneously depress the upper transparent plate to act an excessive force onto the transparent plate or its opening/closing mechanism to result in decisive damage thereto. Furthermore, when the pair of transparent plates are kept open for a long period of time, a foreign material such as dust enters therebetween. At the subsequent retrieval, a projected image and a print image obtained by copying the projected image are degraded due to the presence of the foreign material. In addition, the foreign material causes incomplete contact between the microfiche and the pair of upper and lower transparent plates and this may lead to a focusing error. In the worst case, the microfiche is scratched.
Even if the upper transparent plate is kept open while the operation has not been performed for a long period of time and the power switch has been kept off, the problem described above also occurs.
The upper transparent plate is kept open for a long period of time mostly when the operator forgets to turn off the power switch after the used microfiche is ejected. Power consumption is wasted, and lifetime of the projection lamp or the like is shortened.
Furthermore, when the previous user turns off the power switch while the used microfiche is left between the upper and lower transparent plates, the subsequent user does not know that a microfiche is left between the transparent plates. The subsequent user inserts a new microfiche between the upper and lower transparent plates and forcibly squeezes the previous microfiche into a connecting portion between the upper and lower transparent plate, resulting in jam or damaging the previous microfiche.